1. Field of the Invention
This invention relates to a means and method of bevelling glass workpieces, particular industrial optical glass workpieces, in which a workpiece is placed between tiltable work plates mounted in adjustable, spaced apart relationship on a movable carriage and wherein a workpiece edge to be bevelled projects downwardly of the work plates and between the space therebetween, and wherein the carriage is moved past a grinding wheel mounted underneath the space between the work plates so that the workpiece edge is bevelled by contact with the grinding wheel.
2. Description of Related Art
The optical glass industry has been in need of a dependable, user friendly glass beveller. Glass blanks need to have bevelled edges for varying reasons, such as:
1. ease and safety of shipping because glass is an amorphous crystal solid in which square edges are readily broken:
2. glass blanks for a wide variety of applications need to be held or positioned for processing by mechanical devices that tend to mishandle square edges;
3. specific angles needed by specialty optical glass products are really exaggerated bevels, and
4. edges of lenses are held firmly in positioners used in the optics and laser industries, and those edges have to be bevelled in an exact manner.
The industry needs:
1. more control over the bevelling process in order to insure achievement of accuracy to definite standards;
2. to conduct the bevelling process with as little human error as possible;
3. to provide accurate, dependable repeatability;
4. to handle routinely varying sizes and shapes of glass blanks, and
5. simplification of the mechanical aspects of a process that requires nearly immeasurable accuracy.
U.S. Pat. No. 4,322,915 provides a device for bevelling an edge of a glass workpiece by moving the workpiece edge laterally into contact with a rotating abrasive bevelling cone section of desired, fixed inclination. Such devices have the disadvantage of having to change the abrasive wheel cone for each separate angle of bevel required.
U.S. Pat. No. 4,493,167 is directed to a device for bevelling an edge of a glass sheet held in position between a pair of moving belts. Such apparatus has the disadvantage of being useful for bevelling only a single glass shape, i.e. sheets.
U.S. Pat. No. 4,501,091 is concerned with apparatus for bevelling an edge of a cylindrical optical glass workpiece. This device, too, is limited to the bevelling of a single workpiece shape.